Physicians and other skilled personnel customarily specify the ventilation of a patient based on physiological parameters. Typically, the specified ventilation is in terms of tidal volume, minute volume, breath rates, and inhalation to exhalation ratios.
A persistent problem in this field has been that heretofore time consuming and complicated human procedures have been required for adjusting prior art ventilators, such as anesthesia respirators, to deliver the required ventilation. The procedure generally involves the use of a watch for timing pneumatic equipment operations and determining the number of breaths per minute, the minute volumes and inhalation-exhalation times. While performing these functions, the timing person is required to adjust a multitude of respirator controls until the desired ventilation is achieved. In doing so, the human being, rather than the equipment, controls when the appropriate minute volume, tidal volume, breath rate, and inspiration-expiration ratios are achieved.
In view of the foregoing, a need has heretofore existed for flow control facilities which eliminates the prior art manual timing and adjustment procedures and automatically regulates the flow by the direct setting of minute volume, breath rate and inspiration-expiration controls.